Abstract
O-acetyl-L-serine (OAS) is shown to be as a positive regulator of sulfur-responsive genes. OAS levels in tissues are changed in response to S/N ratio in culture media, but a number of other factors controlling OAS levels remains to be elucidated. It is also unclear how OAS regulates sulfur-responsive genes. To address these questions, mutants exhibiting altered expression of sulfur-responsive genes were isolated.
The β subunit gene of soybean β-conglycinin is one of the sulfur-responsive genes. Transgenic Arabidopsis, NOB, in which response of the b subunit gene was visualized using GFP, was generated. In one of the mutants showing higher GFP fluorescence, expression of endogenous sulfur-responsive genes and OAS concentration was higher. This mutant was named as osh1-1 (OAS high accumulation). No base change was found in the mapped region. However, demethylation and increase in mRNA level was found in one of the genes within the mapped region.
